In the technology in transmitting data through the USB (Universal Serial Bus), the transmission device is classified into three modes, according to the transmission speed: The low speed mode, the full speed mode and the high speed mode. In transmitting data through the USB interface in each of the above-mentioned modes, the USB specifications and standards shall be completely followed. The USB standards leave little space for designers to develop devices that use the USB interface, in the data transmission mechanism.
In addition, in the conventional USB data transmission devices use independent upload nodes and download nodes to provide the bidirectional data transmission functions. Various designs and transmission methods may be used in realizing the data transmission. Therefore, it is difficult to provide a new mechanism that provides higher data transmission speed and is usable commonly in all or most of the available transmission methods.
Several solutions have been proposed in enhancing the data transmission speed in the USB interface. One proposal is called the “Double-Buffered Transfers” that expands the data buffering space in the data buffers at the upload/download nodes, whereby the data are transmitted in a “ping-pong” manner. This solution reduces the waiting time needed in moving the data to be transmitted, whereby the transmission speed is made higher. However, while the data buffer space at the upload nodes and the download nodes is expanded, the cost of the device is made higher as well.
Therefore, it is necessary to provide a new mechanism for the USB interface data transmission device that provides higher data transmission speed, without suffering from the higher manufacture costs.